Radiant energy resonant vibratory system



Aug. 24, 193 7.

w. H. PRIESS 2,090,853

RADIANT ENERGY RESONANT VIBRATORY SYSTEM Filed May 11, 1934 3 Sheets-$heet l IN VEN TOR Aug. 24-, 1937. w. H. PRIESS RADIANT ENERGY RESONANT VIBRATORY SYS TEM Filed May 11, 1934 3 Sheets-Sheet 2 INVENTOR Aug. 24, 1937. PRIESS 2,09Q853 RADIANT ENERGY RESONANT VIBRATORY SYSTEM Filed May 11, 1934 5 Sheets-Sheet 3 INVENTOR Patented Aug. 24, 1937 UNITED STATES PATENT OFFICE SYS William H. Priess, New York, N. Y., assignor to International Television Radio Corporation,

New York, N. Y., a corporation of Delaware Application May 11, 1934, Serial No. 725,128

' 23 Claims.

There are two general systems of television in use today. These systems are the cathode ray types and the scanning disc types. The former employs a cathode ray in an evacuated vessel and the ray in that vessel impinges on a fluorescent screen at the end of the vessel. Electrostatic or electromagnetic control elements are provided within the vessel for swinging the ray along the screen, and a device is connected to the generating system for the ray to vary its intensity. The cathode ray paints a picture on the fluorescent screen in synchrony with the scanning of the subject at the studio. The intensity of the ray at each point is made to follow the intensity of the photoelectric light pick up, point by point, at the studio. The pictures are. repeated twelve times or more a second to provide the illusion of continuity.

The scanning disc system employs a series of openings, mirrors or lenses which physically travel across the source of light and paint a picture on the source of light or its projection to the screen. The travel of the opening or lens is synchronous with the scanning at the studio.

The intensity of the light is likewise made to follow the point by point intensity of the light reflected from the subject in the studio.

The main objections to the cathode ray type are its low light intensity and its limited size of picture. If the picture is to be made larger the bulb assumes dimensions that produce a very expensive instrumentality, inasmuch as the structure must be sufiiciently strong to resist the-atmospheric pressure of 15 pounds to the square ;inch of surface. 'There is some possibility that the picture itself might be projected from a tube to a larger external screen, but so far no pro nounced success has been attained in the development of such a device.

40 The objection to the scanning disc type of system is that it involves a moving mechanism of considerable size that must be whirled at great speed in order to produce a scanning of sufficiently fine texture. If the scanning discincludes a system of whirling lenses each of the lenses must be matched and set to an extraordinary degree of relative accuracy so that their projected light is placed in a correct relative geometrical position on the screen. The very fact that the disc is whirled at a high rate of speed introduces a grave problem of maintaining the accuracy of this initial setting. However the scanning disc type itself presents. an advantage 3 over the cathode ray type due to its possibility of using a light source of any desired intensity and its possibility of projection.

The scanning disc type sufiers, in addition to its inherent mechanical difficulties, from the nature of its scanning which is by parallel lines con- 5 tacting with slight over-lapping with a preceding and succeeding parallel line. If a slight inaccuracy of the scanning disc or of the lens system is present, black bars appear between the lines or bright edges occur between the lines in the region of the over-lapping. Its multiplicity of optical systems require an accuracy of co-' ordination as well as individual accuracy of each optical system.

To overcome the difficulties inherent in both of-the present used systems,,I have devised and it is my object to teach and disclose a system retaining the main advantages of each system and eliminating their faults. In my system I scan a picture harmonically by swinging a point 20 of light across a screen and retu ning the point of light to a point one line lower at the opposite side of the screen at an angle which eliminates horizontal bar distortion. Furthermore, I sweep in the picture from bottom to top and from top to bottom harmonically, so that a greater persistence is obtained on the forming of the picture and the flicker caused by its interruption is reduced. In my fundamental mechanism I employ an amplifier for receiving and amplifying the energy to a point suflicient to operate the chosen light source, a condensing lens system for molding the source into a beam of desired characteristic, one or more oscillating mirrors whose function is to sweep the beam into a line, and to sweep the line, to trace and frame the picture on a screen.

In order to obtain a high degree of definition in the picture, it is essential that each picture be made up of a large number of dots of light. 40 When placed on the subject they are of course of varying intensity. The larger the number of dots present in a picture, the greater the definition of the picture and the more nearly that picture reproduces the record of the human eye. A photograph with its many tens of thousands of dots of varying intensity per square inch is an ideal visual record of a subject. In television such definition would require modulation ire-- quencies exceeding the breadth of band that might be utilized for this purpose, so that its definition must be of an order of magnitude lower than that of a photograph. In the standards now employed in the Nipkow disc system, approximately 4300 points of light define a picture. It is not practical to increase this greatly in the Nipkow system because of the tremendous increase of speed and diameter of the disc that would follow, and thecost of a multiplicity of 5 accurate lenses or mirrors. Devices of large diameter running at high speed are not suitable for the home. For example, if lenses in diameter are used, to provide twice the number of dots, the disc would have to be approximately 30" in diameter and its periphery speed would be approximately 1% mlies per minute. The power consumed by windage would require a motor in excess of one H. P.

With my system the motion of the resonant vibratory elements is very slight, a matter of a few thousandths of an inch. In the adaptation to television and facsimile signalling, which is one of my objects, I emplo as part of resonant vibratory elements, and preferably integral therewith, a high speed mirror, and the number of lines scanned is readily raised from 1200 to 5000 lines a second. A larger number of lines is possible with a refining of design both as to the reduction of the moment of inertia of the oscillating masses and in increase of the elasticity of the system. A further increase would be obtained by placing the oscillating mechanism in an evacuated vessel. This is highly practical because the oscillating mechanism itself is very small mechanically.

The mirror can have two independent degrees of motion at rightangles to one another, or two separate mirrors may be employed to obtain the desired scanning motions.

The low speed motion being at a frequency of from 15 to 60 cycles a second presents no difficulties. The high speed motion however has inherently the difficulty connected with the high acceleration of a mass.

I have found that by employing the principle of mechanical resonance that I can reduce the driving powers to a very marked degree, and generally several orders of magnitude below the power that would be required by a design operated 5 without this principle.

In my invention, I energize an armature that is of such character that it is mechanically resonant to the driving forces. Two preferred forms are employed. First the armature mounted on 5 an elastic torsional rod, or a portion of the rod polished to form the mirror and vibrated about the axis of the rod, and second, the armature is mounted on a beam spring, fixed to be flexed about a fulcrum, and upon the end of which is 55 fastened the mirror or its equivalent. This resonant mechanism may operate a clock, a sound device, electrical circuit contactors and like devices.

The driving force may be derived from a our- 5 rent applied directly to a conducting loop mounted on the reed, an induced current in a conductin'g element mounted on the reed, or a magnetic field reacting upon a magnetic element mounted on the reed, or acting on the reed itself if the 5 latter is magnetic. In the last case, the polariz= ing of the magnetic element on the reed, in a proper manner, increases the effectiveness of the forces applied to vibrate the reed, and in the first cases a polarizing field reacting with the 7 field generated by the applied current or induced field, is aiso effective in increasing the useful forces.

In one embodiment it is my further object in my invention to use a torsional rod, oscillating 75 with its masses at resonance. I prefer likewise P: 21r LA where P is the period A is the modulus of elasticity I is the moment of inertia about the axis of rotation A is the radius of the rod L is the length of the rod.

In general in the dimensions I employ, I find that the moment of inertia of the rod itself is but a second order of magnitude compared with the moment of inertia of the mirror and driving system In a preferred form for television and facsimile transmission the mirror is fastened to a torsional rod by welding, braising, forcing or the like. Cne end of the rod is braised or welded into a firm support. The other end is made to terminate in a rectangular section that may be gripped firmly by a pair of adjustable jaws to provide a means of adjusting the elasticity of the system by a continuously variable element. The polarizing and driving magnetic systems are fastened to the support. This constitutes the high speed or iine frequency system. 7

In order to provide a low speed frame or picture frequency system, the rod, mirror, its magnetic systems and supports are fastened to one end of a second torsional rod, whose axis is at right angles to the first rod and whose axis crosses the center of the plane of the mirror, and lies in that plane. The other end of the second torsional rod is welded or brmsed into a support that is firmly fastened to the base. On the far side of the line frequency system support is fastened a rectangular elastic element that may be clamped to the base by a movable jaw, so as to provide a means of adjusting the elasticity of the picture frequency by a continuously variable element. The long axis of this rectangular elastic element coincides with the axis of the second torsional rod. The driving magnet for the picture frequency motion, is fastened to the base and so magnetically related that it operates upon a magnetic portion of the system it actuates that has been polarized by the polarizing coil previously mentioned.

Bepending, as it does, upon the laws and principles of resonance and harmonic motions, my power consumption may be relatively extremely small in building up the desired torque on my oscillating vibratory system, to cause it to swing through the desired arc. This may be compared to the principle of resonance in an alternating current circuit, (i. e. when 'the inductive reactance is just equal to, and hence neutralizes the permittive reactance) where the current will attain enormous values.

The system I have invented is not only efficient, rugged and inexpensive but has an inherent accuracy due to the employment of a periodic principle in actuating a device to record a periodic recurring phenomena, as distinct from the use of principles employing an element of dis-.

continuity for this purpose. Furthermore it has the stored energy feature which makes its record smooth, if a pulse is lost, and its travel independent of the wave form of the driving pulse.

My invention will be more readily understood by reference to the accompanying drawings in which like numbers refer to like parts in the several views.

' Figure 1 is a perspective elevation of a preferred form of resonant system with a single mirror.

Figure 2 is a sectional elevation along the plane YY of Figure 1.

Figure 3 is a partial sectionalized plan view along the plane xa: of Figure 1.

V Figure 4 shows a form where the motion of the resonant armature is obtained by fiexing a flat strip of spring steel.

Figure 5 shows a diagrammatic view of a form of drive for the resonant system, comprising a loop of conducting material fixed to a torsional rod and threaded by a magnetic circuit.

Figure 6 shows a schematic radio and television equipment with designated circuit connection and elements therefor.

Figure 7 is a diagrammatic view of one form of facsimile transmission available-with my device and Figure 8 is a view of the receiving portion of same. I

Referring toand describing the figures in more detail, in Figures 1, 2 and 3, the numbers on these three sections are corresponding parts. (I) is the high speed torsional rod, (2) the elastic variable of this rod, (3) the mirror, (0) the armature, (5) the welded junction of the rod and the rod support, (6) the rod support of magnetic material so related as to saturate the rod (I) and its armature (4) with the polarizing field from the coil (1), ('1!) the polarizing coil, (8) the insulated bobbin upon which the coil is wound, (9) a pole piece for this field which acts as an armature for. the low frequency field from the A. C. magnet (I0), (III) the A. C. magnet and core energized by current of picture frequency the same as the mechanical frequency of the system upon which it acts, (II) the line frequency magnet, (I2) the coils for the line frequency field energized by a source of current of the same electrical frequency as the mechanical frequency of the system upon which-it acts, (I3) non-magnetic frame joining the parts, (I4) jaws for gripping the elastic variable (2) of the rod (I), (I5) screw for locking the adjustment of (It), (I6) nut for adjusting the position of (M), (II) ball lock for measuring themotion of (I l), I8) is the low frequency torsional rod fastened to the frame (I3) and the base (I9), (I0) the base, (20) the elastic variable for varying the low frequency period, (2|) jaws for setting the low frequency period, (22) locking mechanism for (2!), and (23) tension holder for (20).

The torsional rods are of steel music wire.

The high speed rod is 0.080" diameter. The

for a frequency of 24 cycles per second. Under these conditions the angle of motion in each direction is about 7.5 degrees, giving a light angle of about 15 degrees.

It is advisable to make the mirror integral with the rod, as distinct from a design where the mirror is cemented, or clamped to a support that has been firmly fastened to the rod. This is due to the fact that the motion during the 1 transient building up stage is logarithmic and the summation of motions that are separately measured in millionths of. an inch increase per swing. If the play between the mirror and rod is of this order-of magnitude the system will not build up, but the energy will be dissipated I by friction at the insecure joint.

Preferably I use a fine texture metal for the mirror. I brase or weld it to the rod and grind and polish it to as near a perfect surface as possible. If the material of the mirror is oxidizable I plate it with iridium or rhodium, or other metal that has good reflection properties and yet resists corrosion. I have made satisfactory mirrors of stainless steel" that require no plating operation.

I prefer to mount the mirror to project slightly above the surface of the mounting rod so that the grinding and polishing operations are simplified. In grinding and polishing I prefer to imbed three rods and mirrors equally spaced in a holder in a wax or moldable substance, and find that in this manner that the planes of. the mirrors can be best maintained.

Although it is practicable to have the mirror element serve the dual function, of driving armature and mirror, I prefer to have the driving armature a separate element constructed of magnetic material that is more desirable for this single function, for example silicon steel.

In Figure 4, (IA) is the mirror, (2A) the reed fastened to the polarized polepiece, (3A). The length of (2A) can be varied and locked by the yoke (4A). The A. C. magnet core is (5A and its coils (6A). The polarizing coil is ('IA).'

In Figure 5, (IB) is the polarizing pole piece, (23) the short circuit loop, (33) the core of the alternating curent field, (4B) the torsional rod, and (5B) the mirror.

Both the forms shown in Figures 4 and 5 may be-designated so that there are two independent motions given to the same mirror, by mounting these systems as previously shown.

The damping of the system other things being kept equal, can be varied by a proper choice of theamount of inertia and elasticity of the system. There is one value of elasticity that satisfies the frequency equation for each given value of moment of inertia. However, maintaining a constant ratio for a. given frequency we can increase the product of these factors and thereby decrease the damping. The damping can be further decreased by decreasing the friction of the system.

These resonant electro-mechanical structures canbe used for purposes other than television with some simple modifications specific to the particular .use.

In Figure 6 is shown a diagrammatic illustration of elements and circuit connections in a form for television. At A I show the subject to be televised, at B, the scanner, at C the source of the light for scanning the subject. D and E are respectively the frame and line frequency oscillators. F is the photoelectric cell. G the amplifier for magnifying the current variations in F. H is the oscillator for the carrier wave, that is modulated by G to produce an envelope corresponding to the current in F and further modulated to produce synchronizing pulses of the frequencys of D and E. I is the antenna for radiating the modulated output of H. J is the antenna for collecting the energy radiated from I. K is the receiver which tunes to the carrier and amplifies the received energy from J, filters out the frequencies E and D, amplifies these frequencies and adjusts their phases and amplitudes and feeds them to the scanner N. The energy of J with the frequencies D and E removed is further amplified and impressed upon the Kerr cell M. L is the source of light at the receiver. M is a Kerr cell. N the scanner. Os is the screen, and P the picture formed upon the screen.

The upper portion of Figure 6 shows a conventional sound channel. Q is the microphone, R the amplifier for the sound frequency currents, S the oscillator and its modulator, T the antenna for radiating the carrier frequency modulated into an envelope to follow the sound frequencies, U the antenna for collecting the radiation from T, V the receiver which tunes to the carrier frequency, amplifies and detects and feeds the output to W. W is the loud speaker or device to transform the electric currents to sound waves.

Also in Figures 7 and 8 I show an adaptation for facsimile transmission. In Figure 7 I show the transmitter. ID is the scanning mirror, 2D the'subject matter continuously moving across the slit 4D in the direction of the arrows. 3D is 'the opaque frame containing the slit 4D, 5D the source of light, 6D its optical system to produce a fine line or spot at 4Dto illuminate an element of the subject matter, ID a lens for collecting the light transmitted thru the subject matter 2D, and focusing it upon the photo electric cell 8D.

In Figure 8 I show the receiver where, IE is the scanning mirror, 2E the film moving continuously in the direction of the arrow across the slit 4E, 3E the opaque mounting for the slit 4E, 4E the slit, 5E the source of light, 6E one of the pair of Nichols prisms, and 1E the Kerr cell for modulating the light and 8E the optical system of SE. The subject matter sheet at the transmitter transparent or translucent, and the characters opaque. This sheet'is driven at a constant speed across the slit. The scanner projects a beam of light parallel to the slit. The slit defines the light in a vertical direction. The transmitted light is collected by a lens and projected to a photo-electric cell, whose varying current is magnified to the desired level by an amplifier. The output of the amplifier may be sent by wire, or used to modulate a carrier wave. The scanners at transmitters may be synchronized by a special circuit for this purpose or a portion of the scanning time interval may be reserved for this purpose. In practice, the photo-electric cell, slit, scanner and light source, are enclosed in a light box to exclude outside light.

At the receiver the film, slit, scanner and light source are likewise enclosed in a lightproof box. The film is made to move with the same speed across the slit as the subject matter at the transmitter. tical direction. Any difference in the two speeds is a direct but not an accumulative distortion. The film after exposure can be made to pass progressively thru its developing, washing, fix- The slit defines the light in a vering and drying processes, and if desired a duplicating printing process for record purposes, thus providing a rapid and continuous facsimile system.- By controlling simultaneously the start and stop of transmitter record material and film, with a cut off of the latter to prevail a disturbance of the timing of the chemical processes, the system may be interrupted at will.

To transmit stills or facsimilic communication, I may thus employ but one mirror motion at the transmitter and receiver, and have the trans mitter copy and receiving film move slowly across a slit that limits the vertical scanning at the transmitter and the vertical exposure at the receiver. Preferably the copy at the transmitter is an endless roll of film, either positive or negative, and the film at the receiver likewise an endless roll of unexposed sensitive film. process may be made a continuous one at both ends and the speed of travel of the two rolls need not be exact, for the distortion is only directly proportional to the two speeds and not accumulative.

When used in television I either employ one of the scanner devices as the control of a fiying spot of light to scan the subject and pickup the light reflected from the subject as a current from a photoelectric cell, or collect its light from an illuminated subject by this scanner and impress it upon a photoelectric cell. The subject may be the primaryobjects themselves, or a reproduction of these objects such asa photograph or drawing, or a photographic film in either positive or negative. Film is an ideal subject. At the transmitter I require two electrical oscilla- The tors or generators to provide the line, and picture insert a phase adjuster in the output of the amplifiers that supply the receiver scanner with power. This device comprises two primary coils at right angles connected in the output plate circuit. One of the coils has a condenser in series of such value as to obtain a 90 shift in phase, and a resistance to make both coils of the same "eifective ampere turns. In the field of the coils I place a rotatable coil of an inductance equal to that of the scanner coil that it supplies and in series with this connection a condenser of such value'as to make the impedance of the system a minimum. An automatic voltage limiting tube can be inserted in the amplifier to provide a constant amplitude for the scanner pulse or a manual setting may be employed by placing a variable resistance in the scanner coil circuit or otherwise as preferred.

Where the picture frequency pulse is locally generated at the receiver. I supply a frequency variable in that circuit as well as a phase adjusting means. 4 4

In order to more efl'ectively distribute the received light from the screen I prefer tomake the screen in such manner that a substantial portion of the light is reflected over a comparatively narrow angle, say 30 of solid angle. ThisI accomplish by making the screen have a translucent granular surface, and backing that surface with a mirror surface. For example, a thin sheet of plain glass frosted on one side and mirrored on the other.

' In addition the effectiveness of the screen can be increased by making its surface of a substance that glows under the action of light and of such a glow persistence that this glow is substantially of a time duration slightly less than the picture frequency.

At the receiving end, I collect and amplify the modulated carrier, I filter out the line of frequency pulse, further amplify it and impress it upon a similar scanner. I do the same to the picture frequency pulse-if one is sent-or I generate a separate picture frequency pulse at the receiver. The output of the receiving amplifier is used to operate a high modulating speed lamp, or to modulate constant source of light by th Kerr cell phenomena.

By means of an optical system the source of light is directed upon the oscillating mirror and reflected as a spot of correct dimensions upon a screen. I may use a source of light as shown in Figure 6, where iC are straight filaments enclosed in evacuated glass cylinders 20, 3C are cylindrical parabolic mirrors placed with iC at their foci, 4C is a condensing lens and 50 the focus of the combined beam.

If the light system at the receiving end is a constant source modulated by Kerr effect, I prefer to use a form of light that has a point emciency greater than that which can be obtained from a glowing large area such as found in the common projection lamps. Since the spot on the screen must be small, the source area must likewise be small since there is a direct relationship existing between the sizes of these two areas. I make the source astraight filament, and place a cylindrical lens in front of each straight section to make the horizontal components of its emis- I sion parallel beams. I then collect this sum thru a condensing lens or mirror and employ the output thru a suitable optical system as 40 a beam on the vibrating mirror after it has passed thru its polarizing and modulating systems. This novel arrangement is equivalent to super-imposing the light of many filaments on to a single summation line and collecting the horizontal components of the light from that line over the angle of the cylindrical lens. The angle of the vertical component employed is determined by the desired projected spot size. As an alternative I employ a cylindrical parabolic mirror back of each filament, placing the filaments at the focus, and a condensing lens or mirror to collect the light into a beam.

In the operation of my system I find it advisable to televise the call of the station from a card that has a well defined vertical and horizontal line crossing in the center. If the line frequency at the receiver is out of synchrony, two Vertical lines show. As the phase adjusting coil is rotated these lines can be made to move towards one another until they coincide, at which point transmitter and receiver are synchronized for line frequency. If the picture frequencies of transmitter and receiver are different the receiver oscillator must be adjusted until the hori- 5 zontal lines no longer drift, at which point both are-in frequency. Then the two may be synchronized by turning the phase adjusteruntil the two horizontal lines coincide.

Inasmuch as the light eificiency of my scanner is very high some minimum amount of steady studio light is permissible, and further, the scanning light may be made more pleasant by employing the combined light of an ultraviolet and infrared beams, with separate and series or parallel connected light cells responsive to each one of these high frequencies, either as a flying spot or direct from the subject. Of course, color filters may be used at transmitter or receiver.

The foregoing disclosure is sufliciently complete to enable anyone skilled in the art to employ my invention, it being understood that certain variations can be made without departing from the scope of the invention, for example the substitution of a vibrating lens for my vibrating mirror, or the use of scanning pulse carried by a separate carrier wave or circuit.

Having thus described my invention, what I claim and. desire to secure is:

1. A two-dimensional scanning device employed in the transmission or the reception of visual images, comprising torsional electro-mechanical vibratory systems driven at their inherent natural periods, carrying an optical element which, at some position in its swing, coincides in time with a condition of substantially zero strain in each of said vibratory systems. I

2. A television or facsimile system, comprising scanning means, electric circuits associated therewith, said scanning means comprisihg torsional electro-mechanical' vibratory systems driven at their natural periods carrying an element having a surface reflective-of radiant energy which, at

some position in its swing, coincides in time with a condition of substantially zero strain in each of said systems. I

3. An element in a television or facsimile system, comprising two mechanical systems mounted without substantial initial tension for torsional motion, and supporting a single optical element, and means for operating said systems at their resonant frequencies to supply two motions to said optical system.

4. A scanner comprising a single optical device conducting loop, a rod of elastic material firmly attached thereto, a unidirectional field related to said loop, means for threading the loop with an alternating magnetic field to induce in said loop a current having a frequency equal to the natural frequency of the loop with its associated elastic rod.

5. The process of manufacturing an optical device, which comprises the imbedment of a multiple of metal mirror surface elements and a portion of their supports in a binding eutectic the elements being slightly raised above said supports, and the subsequent grinding and polishing of the mirrors after such imbedment.

6. Means for reflecting or observing reflective radiant energy in variable directions including a surface reflective of radiant energy, a plurality of angularly disposed stiif elongated elements operatively associated with said reflective surface, and means for activating said elements torsionally at different frequencies, whereby said reflective surface vibrates simultaneously in different directions at diiferent frequencies.

'7. Means for reflecting or observing reflective radiant energy in variable directions including a surface reflective of radiant energy, a plurality of angularly disposed stiff elongated elements of different natural periods operatively associated with said reflective surface, and means for activating said elements torsionally to vibrate at their respective natural periods of association, whereby said reflective surface vibratessimultaneously in diiferent directions at different frequencies.

8. Means for reflecting or observing reflective radiant energy in variable directions including a surface reflective of radiant energy, stiff elongated said elements torsionally to vibrate at their respective natural periods of association, whereby I said reflective surface vibrates simultaneously in different directions at different frequencies.

9. Means for reflecting or observing reflective radiant'energy in variable directions including a posed in part at least of magnetic material operatively associated with said reflective surface, and a plurality of electro-magnetic means operating at different frequencies for activating said elongated elements torsionally atdifferent frequencies, whereby said reflective surfacevibrates simultaneously in a plurality of different directions at different frequency in each direction.

10. Means for reflecting orpbserving reflective radiant energy in variable directions including a surface reflective of radiantienergy, a plurality of angularly disposed stiff elongated elements composed in part at least of magneti material.

and of different naturalperiods operatively asso ciated with said reflective surface, and a plurality of electromagnetic means operating at different frequencies corresponding to the natural periods of association of said elements for activatlng each of said elements torsionally at their gated mementand operatively associatgd reflecdifferent natural periods of association, whereby said reflective surface vibrates simultaneously in di fl'erent directions at different frequencies,

11. Means for reflecting or observing reflective surface reflective of radiant energy, stiff elongated elements composed in part at least of magnetic material disposed at right angles to each other, and operatively associated with said reflec- 40 tive surface, and electromagnetic means for activating each of said elongated elements to torsionally vibrate, whereby said reflective surface vibrates simultaneously in right-angled direcsurface reflective of radiant energy, stiff elongated elements composed in part at least of magnetic material of different natural periods disposed at associated with said reflective surface, and electromagnetic means operating at frequencies resonating with the natural periods of association of said elongated elements for activating each of said i 55 elements to vibrate in harmony with the differently possessed natural periods, whereby said reflective surface vibrates simultaneously in rightangled directions at frequencies in harmony with the natural periods of association of said elon- 60 gated'elements.

13. Means for reflecting or observing reflectiv radiant energy in variable directions including 5a surface reflectiye of radiant energy, a stiff elon- 1 gated element operatively associated with said res 65 flective surface, a magnetic armature affixed to said elongated element, and means for applying a;

variable acting magnetic field resonating with the natural period of association of said elongated element, whereby said element and operatively 70 associated reflective surface are resonantly vibrated.

14. Means forreflecting or observing reflective radiant energy in' variablegdirections including a surface reflective of radiant energy; a stiff elon- 75 gated element operatively associated with said angle.

reflective surface, an electrically conducting loop aff xed to said elongated element, and means for threading said loop' with a variableacting magnetic field resonating with the natural period of association of said elongated element, whereby said element and operatively associated reflective surface are resonantly vibrated.

15; Means for reflecting or observing reflective radiant energy in variable directions including a 10 surface reflective of radiant energy, a plurality of a surface reflective of radiant energy, a stiff elonangularly disposed stiff elongated elements coma gated element operatively associated with said reflective surface, means for magnetizing at least a part of said elongated element, and means for superimposing on the activity of said magnetizing of said elongated element a, variable acting magnetic field resonating with the natural period of associaticn of said elongated element, whereby said elongated element and operatively associated reflective surface are resonantly vibrated.

16. Means for reflecting or observing reflective radiant energy invariable directions including a surface reflective of radiant energy, a stiff elongated element op atively associated with said reflective surface mounted to be substantially free from frictional damping for torsional activity, and means torsionally activating said elongated element in resonance with the natural period of association thereof, whereby said elon- Vtive surface are, resonantly vibrated. V

i 17. Means for reflecting or observing reflective radiant energyin variable directions including a. surface reflective of radiant energy, a stiff elonradiant energy in variable directions including a gated element operativeiy associated with said reflective surface mounted to be substantially free from longitudinal tension, and means torsionally activating said elongated element in resonance with the natural peri'od of association thereof, whereby said elongated element and operatively associated reflective surface are resonantly vibrated.

18. Means for reflecting or observing reflective radiant energy in variable directions including a surface reflective of radiant energy, a stiff elongated: element operatively associated with said reflective surface substantially free of stress, and means torsionally activating said elongated ele- V ment in resonance with the natural period of as- 50 a right angle each h and operatlvely 1 sociatigm thereof, whereby said elongated ele- 'ment and operatively associated, reflective sur- :face are resonantly vibrated.

W 19. In combination, afisurface reflective of radiant energy, a stiff elongated element operatively associated with said surface, whereby said surface is capable of observing or reflecting radiant energy within the confines of said angle, and surface means having width conforming to said angle capable of recording impingement of radiant energy thereon, or proportionally transfusing therethrough components of radiant energy, continuously linearly movableacross said path within :the confines of said'angle.

20;*-In combination, a surface reflective of radiant energy; a stiffielongated element operatively associated witl'fsaid surface, whereby said surface is capable of ebserving or reflecting radiant energy Within the confines of said angle,

and means surfaced to be capable of recording :thereon the effects of impingement of radiant energy thereon in proportion to the intensity thereof of width conforming to'said angle, said surface being linearly movable continuously across said path within the confines of said 21. In combination, a surface reflective of radiant energy, a stiff elongated element operatively associated with said surface, whereby said surface is capable of observing or reflecting radiant energy within the confines of said angle,

and surface means possessing varying radiant energy transfusion propensities distributed throughout its surface area of width conforming to said angle, said surface being continuously linearly movable across said path within the confines of said angle.

22. In combination, a surface reflective of radiant energy, a stiff elongated element operatively associated with said surface, whereby said surface is capable of observing or reflecting radiant energy within the confines of said angle,

an opaque surface fronting said reflective sur-' face having a slit t'herethrough positioned in said path of radiant energy of length harmonizing with said angle, and a surface treated to be effectively responsive to desired radiant energy manifestations continuously linearly movable across said slit behind said opaque surface.

23. In combination, the system of claim 6 and an evacuated housing therefor, whereby sound and other undesirable variable air effects are substantially eliminated.

. WILLIAM H. PRIESS. 

